The failure of health providers to translate evidence-based guidelines and resources into practice is a salient barrier to improving health outcomes. GHDonline, an online collaboration platform developed by the Global Health Delivery Project at Harvard, will create Professional Virtual Communities (PVCs) related to several key challenges in health care delivery. These PVCs will enable faster dissemination of clinical knowledge, tools, and guidelines. GHDonline proposes to make the timely, relevant, and critical-but also detailed, technical, and complex- information collected and catalogued by the AHRQ, the Institute of Medicine, the Cochrane Collaboration, and the US Preventive Services Task Force, more accessible to those working with and providing care to underserved populations. During the three-year funding period, GHDonline proposes five specific aims: 1. Establish six new PVCs on GHDonline relating directly to the delivery of care of underserved US populations 2. Recruit 10,000 new members to participate in these new communities, building off an existing network of nearly 7,000 members from 2,100 organizations and 159 countries 3. Hire and train 12 new expert moderators to manage the communities 4. Organize at least 36 structured virtual discussions (Expert Panels) around evidence-based guidelines developed by AHRQ and others 5. Compare members' understanding and application of evidence-based medicine before and after participation in the PVCs, using the Kirkpatrick Evaluation Model